Summer's on it's Way Out...
This happens to be the last weekend of the Summer of 2011 but Autumn will be starting a bit prematurely. A zone of high pressure is settling south and east from Central Canada so the air associated with it has a bite to it...our afternoon highs will average about ten degrees below where they should be...in the mid 60s. That alone isn't that shocking, especially when hanging out in the sun it's plenty warm enough. But, you'll really feel it in the mornings. With high pressure on top of New England, the pressure gradient will relax quite a bit leading to nearly calm conditions overnight and ideal radiational cooling will take place. With dewpoints in the lower to mid 30s, surface air temps will get an opportunity to fall to those levels...with this said, the National Weather Service has issued a Frost Advisory for Northern Worcester County and Southern NH excluding the cities. Do you have to worry about all your gardens? No, most won't get that low but the very sheltered spots will and if you have a favorite plant in a pot bring it in just to be safe.
The high will begin to slide offshore early next week and a moderating trend will begin then too. Highs will creep up closer to 70 and slightly higher as well. Later in the week, the pattern looks to turn a little warmer but as the warmth and moisture return north so do our chances for showers and there could be an extended threat for wet weather as the a slow moving trough creeps our way from the west.